A micro turbine generator is a device which generates power with a generator driven by an air turbine and is in wide use with aircraft, vehicles, and the like. A conventional micro turbine usually has a compressor, a combustor, a turbine, and a recuperator. The compressor compressed an air. Then, the compressed air is introduced into the expansion chamber through the guide channel. The expansion chamber reduces the velocity of the compressed air but enhances the uniformity of the compressed air, so as to prevent the compressed air from having an overly high velocity, or being not uniform, while entering the recuperator to reduce the efficiency of heat exchange in the recuperator and the micro turbine thermal efficiency.
However, the expansion chamber of a conventional micro turbine generator has at least one of the four problems as follows: First, the expansion chamber is too long or too wide; it is because the conventional expansion chamber requires that the diffusion angle of the compressed air in the expansion chamber should not exceed 7 degrees; to restrict the diffusion angle of the compressed air, it is necessary to increase the length or width of the expansion chamber and thus render the expansion chamber bulky. Second, the compressed air experiences overly large pressure loss; the diffusion of the compressed air in the expansion chamber is inevitably accompanied by pressure loss; if pressure loss is overly large, the efficiency of heat exchange in the recuperator will decrease, thereby also decreased the air turbine thermal efficiency. Third, the compressed air has high velocity at the recuperator inlet. Fourth, the compressed air has low uniformity.
Hence, in the field of designing an expansion chamber of a micro turbine generator, to meet requirements of applicable apparatuses, considerations must be given to four design requirements, namely volume of the expansion chamber, pressure loss of the compressed air, velocity of the compressed air, and uniformity of the compressed air. However, application of conventional micro turbine generators to specific apparatuses still can be sophisticated.